1. Field of the Invention
The present invention relates generally to rapid prototyping apparatuses for machining unit lamination substances used for prototyping large scale 3-dimensional objects and, more particularly, to a variable lamination rapid prototyping apparatus for producing a large scale 3-dimensional object which can rapidly and easily machine large scale sheets.
2. Description of the Related Art
Conventional rapid prototyping methods are classified into a curing method of forming a 3-dimensional shape by irradiating a radiation curable material with a laser beam, and a method of forming a desired shape by aggregating granular or lamellar solid material.
Generally, a rapid prototyping process means a process of directly prototyping a 3-dimensional trial product (object) using metal or nonmetallic material, such as paper, wax, ABS (acrylonitrate-butadiene-styrene), plastic, etc., based on 3-dimensional CAD (computer aided design) data. Recently, the range of materials for use in the process has expanded to metal powder, metal wire and the like, so that 3-dimensional objects have been prototyped by various rapid prototyping processes.
In the lamellar materials bonding technologies of the rapid prototyping processes, there are a laminated object manufacturing (LOM) technique which was proposed by Helisys, Inc. of the United States, and a Shapemaker □ technology which was developed by Utah University in the United States.
According to the conventional laminated object manufacturing technique, a 3-dimensional object is manufactured by repeating operations of compressing and bonding laminated paper sheets (0.106 mm or so) using heated rollers and by cutting the bonded paper sheets using a laser. However, this technique is problematic in that, because a laser is used to cut the laminated paper sheets, it takes a relatively long time to manufacture a 3-dimensional object and, as well, the manufacturing costs are very high. Furthermore, because a support unit used for shaping the 3-dimensional object must be removed after the 3-dimensional object is produced, there is a disadvantage in that it takes a long time.
In the Shapemaker II technology, relatively thick pieces of material having a thickness of 25.4 mm or more are cut by a hot wire cutting device having two plotter heads and, thereafter, are stacked and bonded together, thus producing a 3-dimensional object. However, this technique is problematic in that the hot wire cutting device cannot speedily rotate because two plotter heads are provided in the hot wire cutting device. Furthermore, because the hot wire varies in length according to the rotation angle of the hot wire cutting device, it is very difficult to maintain a constant heat capacity of the hot wire. Due to the variation in the heat capacity of the hot wire, dimensional accuracy is deteriorated.
In an effort to overcome the above-mentioned problems, a transfer type variable lamination manufacturing (VLM-ST) technique was proposed in Korean Laid-open Publication No. 2003-4638, entitled ‘INTERMITTENT MATERIAL FEED TYPE VARIABLE-LAMINATION RAPID PROTOTYPING PROCESS AND APPARATUS USING LINEAR THERMAL CUTTING SYSTEM’. According to this technique, sheets 10 mm or thinner and having A4 or A3 size are intermittently fed. Thereafter, in a stationary state, a linear thermal cutting system, which has a cantilever shape and is operated through a 4-axis simultaneous control method, cuts fed sheets while moving in X-axis, Y-axis, θx, and θy directions, thus forming unit lamination substances, circumferential edges of which are inclined at predetermined angles. Thereafter, the unit shaped-sheets are manually stacked and bonded together. The technique of No. 2003-4638 can rapidly and precisely machine the sheets, unlike the above-mentioned prior technique. In addition, it is possible to provide an edge inclination to each sheet. Therefore, this technique is advantageous in that the time, for post-processing which is required after the shaped sheets are stacked, is markedly reduced.
However, in the technique of No. 2003-4638, because the linear thermal cutting system which cuts the sheets has the cantilever shape, the sheets are limited in size. In detail, as the size of the sheet is increased, the length of a translation rod to support the hot wire thereon also must be increased. This causes a reduction in cutting accuracy. Despite the above-mentioned problems, no rapid prototyping apparatus for producing large scale products has been developed. Furthermore, technology for producing large scale products depends on manual labor and is slow.